The present invention relates to an electrical machine, for example, a rotary current generator for power vehicles. More particularly, it relates to such an electrical machine which has a stator which is surface cooled, a claw pole rotor, a stator winding supported by a stator sheet pack and having winding heads extending outwardly beyond the stator sheet pack, a metal housing through which heat is withdrawn from its outer surface by a cooling medium, and a heat conductive material embedding the winding heads and connected with metal housing in a heat conductive manner.
Electrical machines of the above mentioned general type are known in the art. In one of such electrical machines disclosed, for example in the JA-GM 57-65570, in which the stator housing of an electric motor is provided with cooling ribs for heat withdrawal. Together with the ring-shaped spaces on the winding heads of the stator winding, the cooling ribs are filled with a heat-conductive mold resin. The winding heads are completely embedded in the mold resin.
Patent document CH-PS 317,647 discloses electrical machines in which outer gaps of a stator-sheet pack together with the winding heads of the stator winding are cast out or cast around by a casting mass of cast resin or the like. The materials for embedding of the winding heads which are used here provide for a good protection against mechanical damage to the winding heads from outside. However, their cooling properties are unsatisfactory because of unfavorable heat conductive values. Moreover, the resin which is utilized here has a tendency to form air inclusions during hardening, due to relatively high shrinkage.